Our next esteemed speaker to be featured here in preparation for The Future of the Internet 2014: Defining Software Defined Networks is Joseph Marsella.

Joseph Marsella currently serves as Senior Director of Strategic Solutions & SDN at Ciena Corporation. In this role, he is responsible for overseeing the companies market focused solutions including it’s SDN strategy and product offerings. Mr. Marsella has been at Ciena for 16 years, holding a variety of roles in product research and development, engineering, and management of the Packet-Optical Transport and Packet-Optical Switching product lines. Prior to joining Ciena in 1997, Mr. Marsella worked as a software engineer for Nokia Siemens Networks. Mr. Marsella holds a B.S. from Clemson University, a M.S. from Johns Hopkins University, and a MBA from Purdue University and ESCP/EAP Paris.

Joe was kind enough to elucidate on “What is SDN” for us, enjoy:

SDN began as an idea, an idea that we should truly separate the data plane from the control plane thus unleashing greater programmability, innovation and agility out of the network. That we could in essence separate the hardware from the software through standards based flow table provisioning and open APIs. The implementation of such an architecture would break the historical model of vendor specific ASICs, with vendor specific platforms and control planes, with proprietary southbound protocols to vendor specific NMS/EMSs and finally opening up through semi-standardized northbound interfaces to integrate into customer’s BSS/OSS and back-office systems. This new approach would hold the promise of greater innovation opportunities through enhanced network access, lower costs through hardware and architectural simplification, and operational savings through commonality of control, creating what promised to be an undeniably powerful business case for network operators around the world.

Today however the definition of SDN is not so straightforward. The term “SDN” has now expanded from its original definition as an idea, to become almost an ideology, that when taken to its extreme can be defined as: “anything software can do to improve the value of a network”. It has become a rallying call for change in networking that stretches from access to core, from user to datacenter, from mobile to fixed networks and through virtually all layers of the traditional OSI model. It is no longer possible to generically speak about SDN and be assured that the reciprocating party’s reference definition is the same. But with this said, this lack of definition uniformity is not as troublesome as it may sound.

If we were to look at general themes and then attempt to categorize these seemingly disparate ideals into factions they would tend to fall into one of three 1) the Purists – those that remain true to the original definition of SDN, 2) the Pragmatists – those that resonate with the benefits of SDN but aren’t prescriptive on the method utilized to achieve them, and 3) the Operators – those that are looking to finally solve the age old operational and multi-vendor management challenges we’ve faced as an industry for years. There are clearly other factions, beliefs and those that fit into multiple categories but these high level classifications typically capture the majority of existing opinions out in the market today. But to truly answer the question of “What is SDN?” we need to look a little deeper at these suggested classifications.

The purist camp adheres to the true definition of SDN as originated out of Stanford and now formally documented in the ONF. They generally believe in the strict separation of the data plane from the control plane and the implementation of OpenFlow as an open southbound protocol to achieve this. When implemented properly and completely the purist definition represents the true revolution in networking that stands to be a defining moment in networking history. But is the industry ready both from a mindset perspective as well as a technological perspective to realize such a significant architectural transformation? Proof points indeed exist and momentum is clearly in this direction but skepticism also remains, which leads some in the market to more of a pragmatic view.

The Pragmatists also realize that things have to change. They realize that for networks to scale and to enable rapid innovation in a fast moving market that divisions need to be broken and programmability needs to be improved. They also realize that software is the key to enabling such a network transformation and believe SDN represents a unique inflection point on the road to achieving this. But this desire for change is not focused solely on OpenFlow, rather on a more varied set of APIs both at the network element and at the higher layers in the controller. This improved programmability enables the opportunity for innovative applications to be developed that are capable of maximizing existing revenue streams while minimizing cost through greater network knowledge and real-time intelligence. In addition they do not necessarily believe that foundational architectural change is required, that control planes need to be separated from data planes. In short they believe that existing, or in some cases new, interfaces communicating with existing distributed control planes still have a place in the network and that with the proper abstraction and northbound interface modifications a flourishing ecosystem of value-add software applications could be created.

The final more operational focused classification looks at the network operator’s side and seeks to solve the traditional problem of multi-vendor management and service assurance. They tend to recognize the growing trend towards “openness” and view it as an opportunity to break the single vendor equipment to NMS/EMS based solution coupling that has existed for years. To the “Operators” the ability to provide a single interface to provision multi-vendor end-to-end services, the ability to simply view all networking alarms and faults from a single screen, and the ability to see a combined multi-domain and multi-layer topology represent examples of the promise that SDN can deliver. This definition even begins to blur the lines between SDN controllers and traditional EMS/NMSs, making it difficult in some cases to define where SDN beings and traditional management ends. In summary the “Operators” view SDN as holding the promise of
multi-vendor management with enhanced service assurance.

The truth is SDN means all of these things and more. One’s exact definition of SDN is not as important as having a clear understanding of the problems one is looking to address and the risk vs. reward factors one is willing to accept. Ultimately a comprehensively defined SDN solution addresses all these challenges and enables the user to migrate from one to another as their business needs dictate. In conclusion what truly is SDN? – it is both an idea and an ideology both representing a significant inflection point in the networking industry – unlike any we have witnessed before……

Come join the conversation as we explore this question further Friday, 22 August at The Future of the Internet 2014: Defining Software Defined Networks – register now!